PAPARAZZI are not supposed to be popular with the people they shoot. However, even if they do occasionally get thumped or have a limo run over their feet, the relationship with their quarry is symbiotic - an exercise in mutual blood-sucking. When you're a middle-grade celeb, there is only one thing worse than being snapped coming out of the lav at Stringfellows - and that's not being snapped at Stringfellows at all.

Hans Lehmann is a paparazzo of a different, entirely parasitic sort. Firstly, he shoots prototype cars rather than soap stars. Secondly, the manufacturers who make the cars really hate his guts. Ferdinand Piech, the head of Volkswagen, once said of Lehmann: 'If he wants to photograph us, then he's risking his life.' In a different cultural context, that might be taken as a fatwa.

Lehmann, who is 53 and lives in some style in Hamburg, has been pursuing his highly specialised career since the early 1960s. He is a celebrated and wealthy figure but would see his trade having more in common with 007 than with the flashgun-wielding Weegee. (Lehmann's autobiography is dramatically entitled Test Drivers and Car Spies: Adventures with

Secret Automobiles.) He talks of his job only with the greatest reluctance and insists on his wife and business partner, Christa, translating every question and answer - despite having perfectly serviceable English.

Lehmann was brought up near the famous Volkswagen factory at Wolfsburg and, as a boy, used to see VW prototypes passing through town at night. Later, when he became a news photographer, he used a 300mm lens to photograph a replacement for the Beetle which never came to anything. His usual agency was uneasy about the pictures and refused to deal with them. Eventually Bild, Germany's equivalent of the Sun, bought the lot and Lehmann was off on his rather odd career of photographic espionage.

Whereas 007 relies on Q to provide him with exploding pens and collapsible auto gyros, Lehmann gets his kit from the DIY superstore. 'For me, one of the most important things is a ladder. I've bought enough to open a ladder shop,' Lehmann says. When going 'car hunting' he travels as light as possible, his most important tools being a 1,000mm lens and a motor drive that can knock off a whole film in four seconds flat. He never works alone, always travelling with a driver / minder so that he can hang out of the window of his hire car, bang away with the shutter-release and not have to concern himself with the getaway.

Although most manufacturers have their own high-security test tracks, no car can be launched upon the public without first being tested on open roads. This is where Lehmann is free to pounce, unhindered by trespass laws. During the winter you will normally find him sniffing around the frozen wastes of Scandinavia, where manufacturers test their cars in extreme climatic conditions. (The low light levels at such latitudes in the winter months account for many of Lehmann's pictures being a little on the grainy side.) During the summer he can be found scouring various desert areas in the United States, Australia or North Africa.

As you would imagine, Lehmann is extremely cagey about his sources. They clearly include individuals who work for the car manufacturers and over the years a number have been fired, accused of passing him information on the whereabouts of prototypes. (One British manufacturer even brought in John Stalker, the former deputy chief constable of Greater Manchester, to try to establish where leaks were coming from.) Lehmann is also said to have built up a string of informants in Finnish petrol stations, Moroccan hotels and so on.

There are two reasons why Lehmann gets right up the car manufacturers' exhaust pipes. First, in ever more competitive markets, they do not want the opposition to know what they are up to. It takes several years and tens of millions to develop a new model; if some startling new advance has been made, admittedly a rare occurrence these days, manufacturers do not want photos of its gorgeous profile plastered all over magazines - and it's not just the motoring press: Stern, a German news magazine with a huge circulation, has used Lehmann's pictures in the past.

Manufacturers clearly love it, though, when one of the opposition gets 'Lehmanned'. Several Japanese manufacturers have tried to buy sets of photos of other makers' cars from the Hamburger with the long lens. Lehmann strenuously denies ever having sold any to them.

The second, and more important, cause of manufacturers' ire is to do with marketing. The recent launch of the Ford Mondeo was an operation on the scale - and, probably, the cost - of the Normandy landings. Television commercials, press advertising, dealer briefings and PR are all carefully co-ordinated for the big push on the consumer front line. But Ford's surprise attack was made less dramatic by the fact that Lehmann had his photos of the Mondeo in the can and published well over a year ago. He says he stumbled across the car, by accident, near Las Vegas.

'Lehmann can also warn readers not to buy cars that are soon to be superseded,' says Gavin Green, editor-in-chief of Car magazine, with which Lehmann has had a contract for some years. Sales of the Ford Sierra, which the Mondeo replaces, can't have enjoyed rising sales figures once the word was getting round that it was definitely due for replacement - especially when the existence of that replacement was confirmed by pictures.

When Lehmann's pictures started appearing with regularity the manufacturers were incensed. 'In the old days they would try all sorts of threats,' says Green. 'They would cancel advertising in our magazine to punish us. We'd get threatening calls informing us that there would be no more press cars for us to test. They'd forget about it after a year or two - but they still don't like it.' Any aggro from the manufacturers is well worth it, however. Scoops are what Green's readers want, and Lehmann's fees account for the largest slice of Car magazine's budget.

Such is the manufacturers' annoyance at Lehmann's activities that two have taken legal action against him. In the mid-Seventies Volkswagen tried to have Lehmann's driving licence withdrawn, alleging that he had driven dangerously and blocked a road while trying to photograph one of its prototypes. Lehmann's own shots showed, however, that it was VW's test drivers who had blocked the road. The case was dismissed before it even came to trial.

The second litigant was the Rover group. It took action under the law of breach of copyright, and at one stage obtained a High Court order to search the house of one of Lehmann's associates in Britain. A call to the British manufacturer to see what it thought of Lehmann met with a terse 'We don't wish to make any comment.' At Land-Rover, a spokesman was more forthcoming. Did the company feel that Lehmann's activities caused significant damage to its business? 'It's not damage, more an irritant. Spy shots won't make a product fail. If anything, such shots cause us more problems when the magazines allege that they are of a new product when they are not.' A recent scoop photograph (not taken by Lehmann) claimed to be a new Range Rover, for instance. 'They keep alleging it but there is no new Range Rover,' said the spokesman, patiently.

The lengths to which manufacturers go to stymie the efforts of photographers like Lehmann are extraordinary (he is no longer alone in the lucrative business). Disguise is the principal weapon. With the aid of plastic panels and tape, or even canvas tents, they cover up the new car underneath; the result often looks as unattractive as a portable lavatory on wheels. Then there is deception. Audi once put a Peugeot badge on the front of its 100 model, and Mercedes had a label saying Ushido on the back of one of its small saloons. In neither case was Lehmann taken in.

Another option is to place engines and suspension systems inside the bodyshells of rival manufacturers. 'The toughest are now Audi, Rover, Volvo and Renault,' Lehmann says. 'They lack any sense of humour. The French have been hiring a rocket test-centre in northern Sweden which you cannot get into, and they transfer each prototype in a sealed truck. The most careless are Mercedes and Fiat. They just stick pieces of plastic on new cars.'

The worst scrape in which Lehmann ever found himself was in Algeria, which used to be a favourite location for dusty, hot-weather testing by a number of European manufacturers. Following a tip-off, Lehmann was hanging around the El Golea oasis in the Sahara on the look-out for a new Audi 100. The next thing he knew, he was cooling his heels overnight in an Algerian prison - an institution hardly renowned for its five-star room service. 'Audi were friendly with the police and they slipped them some information that there were two spies in the oasis,' he says. 'I hid the films I'd shot in the sand and gave them some others. I went back to get them after we were released.'

Lehmann has also been injured. Sitting in a tree - he spends a lot of time in trees - next to the Ford test track near Cologne, he was trying to snatch some shots of the new Sierra. He lost his footing and fell to the ground, breaking his hand and collar bone. 'They always try to locate every possible gap you shot pictures from previously, and then either chop down your favourite trees or set up a new fence with blinds and nets, so you can no longer see through.'

Another hazard, in these days of computer-aided design, is telling new cars apart when most of them look so alike. 'It has become complicated to distinguish the different prototypes,' Lehmann admits. Had he ever thought about a bit of a change, maybe hanging around nightclubs to snap a few celebrities? It might be an easier life and keep him out of the trees. His answer was as Teutonically single-minded as you might expect: 'No. I'm personally a car nut. I'm not interested in the activities of human celebrities.'-